This application claims the priority of Austrian patent application No. A 1249/2001, filed Aug. 9, 2001, the subject matter of which is incorporated herein by reference.
The present invention relates, in general, to a machine for treating a track extending in a longitudinal direction and comprised of two rails fastened to ties supported on ballast, and more particularly to a machine mounted for mobility on the track and comprising a working device operable cyclically for carrying out work on the track; an odometer for registering a distance travelled by the machine along the track; a non-contact scanning device, associated with the odometer, for detecting a position of a tie; and a control unit for centering the working device in dependence upon the scanned tie position. The invention also relates to a method of treating a track.
A machine of this kind, designed as a track tamping machine, is already known from U.S. Pat. No. 3,762,333. The machine includes a working device in the shape of a tamping unit. In front of the latter, with regard to the operating direction of the machine, a scanning device designed as a pulsor is mounted on a frame of the machine in the region of rail fastening means of the track. The scanning device is designed to respond to the proximity of metallic objects, for example a rail bolt, and to emit a corresponding signal. The distance covered by the machine is registered by means of an odometer. Subsequently, taking into account the known distance between the pulsor and the tamping unit, the machine is stopped with the aid of a control unit in such a way that the tamping unit is centered exactly above a tie which is to be tamped.
Austrian Pat. No. AT 321 347 discloses a machine having an electron-optical control element in the shape of a television camera, enabling an operator to precisely adjust the tamping unit individually to the position of the respective tie to be tamped.
U.S. Pat. No. 5,671,679 shows the use of different kinds of sensors by means of which the position of a tie plate or of a similar target object can be detected and registered in a non-contact manner.
Finally, according to Japanese Pat. No. JP 322707/94 A, it is known to detect the difference between a tie surface and a ballast surface by means of an image processing device formed by a light slot and a camera, and to correspondingly control the lowering of tamping units of a track tamping machine during operation.
It would be desirable and advantageous to provide an improved machine of the afore-described type, and a method, which makes it possible to detect the position of a tie in the track in a reliable and dependable way.
According to one aspect of the present invention, a machine for treating a track is mounted for mobility on the track and includes a working device operable cyclically for carrying out work on the track; an odometer for registering a distance travelled by the machine along the track; a non-contact scanning device, associated with the odometer, for detecting a position of a tie, the scanning device being mounted on the machine above the track and designed as a distance measuring device for registering in a non-contact manner vertical distance measurement values between the scanning device and a tie or ballast surface of the track; and a control unit for centering the working device in dependence upon the scanned tie position, the control unit being connected to the distance measuring device and designed for continuously and sequentially subdividing a measuring span, correlated to the distance travelled, into tie detection sections alternating with ballast detection sections, wherein each tie detection section comprises distance measurement values differing only slightly from one another, while the adjoining ballast detection section is characterized by a sequence of abruptly fluctuating distance measurement values.
A machine designed in this way allows to unfailingly detect and register the position of track ties in a most reliable fashion. An important special, advantage is due to the fact that said detection of the tie position can be accomplished safely regardless of which type of tie is present in the track at any given location. As a result, it is possible to scan and treat without problems even older tracks which may have undergone repeated maintenance cycles including tie renewal, and which therefore may include different types or sizes of ties and/or rail fastenings.
According to another feature of the invention, two distance measuring devices are provided, spaced from one another transversely of the longitudinal direction, each being associated with a separate testing unit. This has the advantage that it is thereby possible to detect even a slanted position of a tie lying askew in the track, and to correspondingly adjust the working device before operation in order to prevent possible damage to the working device or to the track.
The present invention also relates to a method of treating a track extending in a longitudinal direction and comprised of rails fastened to ties supported on ballast, with a machine mobile on the track and having a working device operable cyclically, wherein the distance travelled by the machine on the track is measured during an advance movement of the machine, and the position of ties is scanned in a non-contact manner, the method comprising the steps of continuously obtaining distance measurement values, extending in a vertical direction between the machine and a tie or ballast surface, along a measuring line extending in the longitudinal direction across ties and ballast; storing the distance measurement values and establishing therefrom a measuring curve correlated to the distance travelled; and subdividing the measuring curve into an alternating sequence of tie detection sections comprising distance measurement values varying only slightly, and ballast detection sections comprising a succession of abruptly fluctuating distance measurement values, wherein the beginning of each tie detection section is associated with a first transition point of the measuring curve, and the beginning of each ballast detection section is associated with a second transition point of the measuring curve.
This method provides a sure and reliable way of detecting the position of ties in a track regardless of the type or size of the tie.